1. Field of the Invention
The present invention relates to electromagnetic pickup cartridges and, more particularly, to electromagnetic pickup cartridges suitable for use with stereophonic records.
2. Description of the Prior Art
Electromagnetic pickup cartridges include what have been termed moving-magnet type cartridges or moving-iron type cartridges having either a magnet or an iron piece inserted in a gap formed between the faces of opposing poles. The opposing poles are typically the end portions of a yoke element forming the core of an electromagnetic circuit. The magnet or iron piece is typically connected to a stylus contacting a recording groove in a record so that the magnet or iron piece is vibrated within the gap to thereby vary the total magnetic flux flowing in the electromagnetic circuit and generate an output voltage in coils wound around the yoke elements. For a stereophonic pickup cartridge, two sets of opposing poles are positioned orthognally to one another to form a common gap, and each set is related to a respective electromagnetic circuit.
In these moving-magnet or moving-iron type electromagnetic pickup cartridges, particularly in those designed for stereophonic use, a lack of precision in the dimensions of the common gap directly causes crosstalk distortion between the separate channels. Moreover, these pickup cartridges often have a complicated construction and the magnet or iron piece must be inserted in the gap with great precision. Consequently, it is often expensive to manufacture such pickup cartridges and to provide them with the channel separation necessary for today's market.